Re: If not doing something because it was "inconvenient" was the ciriteria for Brexit..
"why bother making such a song and dance about being denied access in the first place?"
For the same reason that tthe EU is collectively heaving a sigh of relief that Britain's no longer involved: We can't go leaking sensitive shit to the USA anymore and as such our usefulness is majorly limited.
What? You thought the special relationship was because they liked us? You should look up Thomas Jefferson's speech where he promised to destroy the UK as an economic power - something the USA effectively did with lend-lease as the coup-de-grace.
The EU stopped thinking about the USA as a close ally a while back. Threatening to blow Gallileo satellites out of orbit if they didn't shut down when the US demanded it underscored that point, as did the screaming temper tantrums that forced China out of the consortium and got the UK to force through the "No non-EU members" rule as a proxy troll to keep them out.
If you think those premature maser failures weren't industrial sabotage then you should think again.